1. Field of the Invention
The present invention generally relates to tape carrier package, and more particularly to a ape carrier package formed by a TAB (Tape Automated Bonding) technique.
2. Description of the Related Art
In recent years, higher-density semiconductor chips have been developed at speed, and various packages for mounting such semiconductor chips have been introduced.
Among those packages, a tape carrier package utilizing the TAB technique is known. In such a tape carrier package, the intervals between the terminals of inner leads formed on the base film can be narrow so that the tape carrier package can be compatible with a high-density semiconductor chip. As the bumps (electrodes) provided to the semiconductor chip are collectively bonded to the inner leads, the production efficiency can be improved.
FIG. 1 illustrates a conventional tape carrier package 1. The tape carrier package 1 comprises a semiconductor chip 2 and a TAB tape 3. The semiconductor chip 2 has a high density, and is provided with electrode bumps 4 as outer connecting terminals on a surface on which a circuit (not shown) is formed. The TAB tape 3 has a base film 5 made of resin. This base film 5 is provided with sprocket holes 6, a device hole 7, a solder resist 8, electrode pads 9, and inner leads 10.
The sprocket holes 6 are used for transporting the TAB tape 3 in the direction (indicated by arrow Y in the figure), and formed on each side rim of the base film 5. The device hole 7 is a rectangular opening formed in the center of the base film in the width direction (indicated by arrow X in the figure). The semiconductor chip 2 is inserted into the device hole 7.
The solder resist 8 is formed on the outer periphery of the device hole to protect electrode pads and a wiring pattern. The electrode pads connected to outer connecting terminals (ball bumps, for instance) are formed in the region of the solder resist 8.
The base film 5 is provided with a wiring pattern (not shown). One side of the wiring pattern is connected to the electrode pads 9, while the other side is exposed from the solder resist 8 to form the inner leads 10.
The inner leads 10 are arranged at the same intervals as the intervals at which the electrode bumps 4 are provided to the semiconductor chip 2. The inner leads 20 extend inward in the device hole 7. The electrode bumps 4 of the semiconductor chip 2 are collectively bonded to the inner leads 10 by heat compressing, so that the semiconductor chip 2 and the electrode pads 9 (the outer connecting terminals) are electrically connected.
After the semiconductor chip 2 is bonded to the TAB tape 3, the tape carrier package 1 is transported by sprockets (not shown) engaged with the sprocket holes 6, wound up by a reel, and sent to another process.
Since the base film 5 of the TAB tape 3 is flexible, the tension during transportation stresses the inner leads 10. The stress is applied to the inner leads in the neighborhoods of the corners 11 of the device hole 7. Also, the high density of the semiconductor chip 2 makes the inner leads 10 smaller and weaker.
With the conventional tape carrier package 1, there has been a problem that the inner leads 10 in the neighborhoods of the corners 11 are deformed or cut off by the stress applied during transportation.
The same problem may arise when a heating test such as burn-in test is conducted. Since the semiconductor chip 2 and the base film 5 are different in thermal expansion coefficient, there is a thermal expansion difference between the semiconductor chip 2 and the base film 5. This thermal expansion difference results in stress on the inner leads 10 in the neighborhoods of the corners 11. Because of this, the inner leads 10 are deformed or cut off during the test.
The principal object of the present invention is to provide a tape carrier package which can prevent the inner leads from being deformed or cut off even if stress is applied to the inner leads during transportation.
The object of the present invention is achieved by a tape carrier package which includes a semiconductor chip, a film-type member, and reinforcing members. The film-type member has a rectangular device hole formed in a position where the semiconductor chip is situated, and inner leads extending inward in the device hole and bonded to the electrodes of the semiconductor chip. The reinforcing members connect the inner leads at each corner of the device hole, and are integrally formed with the inner leads.
As the reinforcing members reinforce the inner leads at each of the corners, to which excessive stress is applied, to prevent the inner leads from being deformed or cur off. By doing so, the reliability and yield of the tape carrier package can be improved.
The above and other objects and features of the present invention will become more apparent from the following description taken in conjunction with the accompanying drawings.